Filter and means for controlling the pulp level therein



June 3, 1930- J. A. MccAsKl-:LL l1,761,401

FILTER AND MEANS FOR CONTROLLING THE PULP LEVEL THEREIN 'Filed oct. 1,1925 2 sheets-sheet 1 v /A/VE/vro/P JASPER A. MQCHKELL.

I/ 5y www June 3, 1930. J. A, MccAsKl-:LL 1,761,401

FILTER AND" MEANS FOR CONTROLLING THE PULP LEVEL THEREIN Filed Oct. l,1925 2 Sheets-Sheet 2 Y ff-I VvE/vrom JASPER MKELL Arr'owfrs PatentedJune 3, 1930 ra'rlarrr` OFFICE JASPER A. MQCASKELL, F SALT LAKE CITY,UTAH FILTER AND MEANS FOR CONTROLLING THE PULP LEVEL THEREIN Applicationled October 1, 1925.

This invention'relates to automatic feed-` Another object ofthe'inventionvis to pro# vide a feed regulationl forContinuous-ifilterswhich will automaticallystop the filter and l relieve the pressuretherein when t-he pulp in the filter rises above a predetermined level.

.Another object of the invention isto provide automatic means forgradually feeding A pulp into a continuously operated filter. 2Q Variousother objects of the invention will appear as' the description proceeds;

In the drawings, which illustrate one form ofembodiment of theinvention- Figure 1 is an elevational view of a 4filter and feeding andfeed `control mechanism therefor,"

Figure 2 is an enlarged view ofthe pulp levelcontrolling means shown inFig. 1

Figure 3 is an enlarged side view of the controlling means shown inFigure 2. l

Referring morespecifically to the 'drawings, the continuous filter 10,which may be of either the pressure or suctiontype, as iis p well knownin the art, comprises acasing 11 inside of which a series of circularfilter leaves ora drum is mounted upon therotating hollow shaft12through whichthe ltrate is drawnl ofi'. The pulp orsludge is admittedthrough a valve 13 to the desired level and the inside of the casingsubjected to air pressure, such air being supplied through the pipe 14-to ,cause flow of the filtrate through the filter surface in the case ofa pressure filter or the i shaft 12 is subjected to a vacuum in a vacuumfilter toV draw the filtrate therethrough. As the liquid in the p ulp isforced through thc filter surface the cake is deposited on the outsidethereof and as the filter revolves with the ho-llow shaft 12, the cakeis scraped off the surface and deposited outside the sludge Serial No.59,759.

tank. The level of the pulp in the filter should he kept below thetop ofthe sludge tank so that none of the sludge flows over the sides thereof.To effect this the flow of pulp into the filter is automaticallycontrolled by the valve 13 which is balanced so that its operation willnot be affected by a difference 1n pressure and is operated by a pistonin the air cylinder 16. Airis admitted to the cylinder 16 through apilot valve 17, which is in turn controlled by the float 18 through thelever 19, the shaft 20', the lever 21 and the link 22. The float 18 israised and lowered by the pulp in the filter and when the pulp risesv toa predetermined level the fioat 18 actuates the pilot valve 17,admitting air into one end of the cylinder 16, which closes the valve 13so that no more pulp is admitted to the filter; When the level of thepulp lowers, the float'V 18 is lowered, the pilot valve 17 is actuated'thus admitting air into the opposite end of the cylinder 16, and thevalve 13 is opened, allowing the pulp to flow into the filter.

An electrical emergency cutoff is provided which operates in case thevalve 13 does not close properly and the pulp continues to flow into thefilter. A contact arm 23 is attached to the shaft 20 and when theA float18 has. moved upwardly a predetermined distance past the normal highlevel of the pulp, the contact arm 23 presses against the button 24, andan electric circuit is closed through the solenoid 25, which raises thelever 26 and turns the three-way cock 27, thereby shutting off the highpressure air flowing through the pipe Q8 and allowing the air in pipes29 and 3() to the filter and monte-jus 31 respectivelyy to escapethrough the exhaust port ofthe cock. rlhis relieves the pressure in thepipe 14 and in the filter casing and also in a manner to be hereinafterdescribed prevents more pulp from being forced into the filter from t-hemonte-jus. If desired, the escaping air off the driving power of thefilter.

.In order to force the pulp into the filter, an apparatus commonly knownin the artas a monte-juslis used. rhis device comprises a tank 31 whichcommunicates through an opening in the bott-om and a T-connection 32 maybe made to throw a switch and thus shutA with the feed pipe 33 and thefilter 10. Swing-check valves 34 and 35 are placed at eitherI side ofthe connection 32 and are so placed that pulp may pass through them onlyin the direction of the filter. The compressed air pipe 30 opens intothe top of the tank or monte-jus and airflow therethrough is controlledby a three-way cock 36. This cock is operated by the air cylinder 3Twhich is controlled by a pilot valve 38 similar to valve 17. A float 39is attached to the shaft 40 extending through the walls of the tank bymeans of the lever l1', and an arm 42 and link @t3 communicate themovement of the float 39 to the pilot valve 38. Hence when the fioat 39is caused to movc upwardly by the rising of the pulp in the tank 31, thepilot valve 33 is actuated, admitting air into one end of the cylinder37. The three-way cock 36 is then operated by the piston in the cylinder37 to stop the escape of the air being exhausted from the tank 31 bytheraising of the sludge therein, while at the same time compressed air isadmitted to the tank 31 through the threeway cock 36 to put the sludgein the tank un der pressure and cause it to flow into the filter whenthe valve 13 is open.

The operation of the system is as follows:

Pulp is fed by gravity or any suitable means through the feed pipe 33and check valve 35 into the tank 31 of the monte-jus. As the exhaustport of the cock 3G is opened the air in the tank passes out through thecock and allows the pulp to rise in the tank until it raises the float39. Raising the fioat 39 closes the exhaust port of the cock 36 and atthe same time allows high pressure air to )ass into the tank 31 throughthe pipe 30. I` he pulp is forced downwardly by the air and as the checkvalve 35 closes under the pressure, it can only pass through the checkvalve 34 and up through the open valve 13 into the filter. Then thelevel of the pulp in the tank 31 has fallen sufficiently to lower thefloat 39, the compressed air is shut off, already described, and the airin the tank is allowed to escape through the cock 36 and pulp flows intothe tank as before. The pulp already in the .filter is prevented fromcoming back by the check valve 34. The operation just described isrepeated until the pulp in the filter has risen high enough to raise thefloat 18, at which time the valve 13 is closed by air admitted into oneend of the cylinder 16 and the flow of pulp into the filter is shut off.

A reducing valve 44 is placed between the filter and the pipe 29 andmaintains the pressure in the filter at a little below the pressure inthe monte-jus, so that the pulp will flow gradually into the filter. Apipe 4-5 admits air through a reducing valve 4h into a box surroundingthe hollow shaft 12 at the end of the filter, such air being underslightly greater pressure so that it will fiow through certain passagesin the shaft 12 and in reverse direcscribed in my Patent No. 1,266,133,May 141-,

It will thus be evident that I have provided a simple and efficientsystem for feeding pulp to pressure filters by which the pulp isgradually fed into the filter and a predetermined level of pulpmaintained therein, the means for controlling the flow of pulp includingemergency electrical means for shutting down the filter if the means forstopping the flow of pulp into the filter should become defective in anyway as by a stick lodging in the valve 13 and preventing its closure.

In place of the check valves 34 and 35, air operated balanced valves maybe used, voperating from the float 39 in the same manner as the cock 36is operated, and connected so that the opening of one valve causesclosing of the other and vice versa. These balanced valves insure smoothoperation and open and close regardless of pressure differences acrossthe valves.

The use of an automatic monte-jus removes the necessity for a pressurepump and eliminates the cost of operating the pump and by maintainingthe pressure in the monte-jus only slightly higher than that in thefilter a gradual fiow of sludge into the filter is asfA sured instead ofthe rush of sludge under the pressure of a pump.

lVhile I have described the system as applied to a pressure filter, itis evident that it may be equally advantageous in use with vacuumfilters or under any conditions Where a gradual controlled feed isrequired, and I do not, therefore, desire to limit the invention to theform of embodiment illustrated-in the drawings, but to interpret theinvention broadly within the scope of the appended claims.

I claim:

1. In combination with a continuous rotary pressure filter of the classdescribed, automatic feed control mechanism comprising a monte-jus andmeans to operate it, a balanced valve, means in said filter to controlsaid valve, an electrical circuit adapted to shut off said monte-jusoperating means when said balanced valve reaches a predeterminedposition, and a connection between said monte-j us and said balancedvalve to prevent fluctuations in pressure and pulp level in said lter.

2. In combination with a continuous rotary pressure filter of the classdescribed, automatic feed control mechanism comprising a monte-jus,pressure means to operate said monte-jus, valve mechanism controllingthe pressure in said monte-jus, valve mechanism in said filter adaptedto limit the intro duction of pulp in said filter, and electrical meansto stop the introduction of pulp to said filter and the operation ofsaid monte-jus yvhei the pulp rises above a predetermined eve 3. Incombination With a continuous rotary pressure filter of the classdescribed, a monte-jus, said monte-jus and said filter being operatedfrom the same pressure source, a balanced valve in'said filter and abalanced valve in said monte-jus, said valves simultaneously operatingto prevent changes of pressure or changes in level in the pulp in saidfilter.

4. In combination with a pressure filter of the class described,automatic feed control mechanism adapted to continuously supply saidfilter With filter pulp, said mechanism Comprising a monte-jus, an inletvalve for said filter, a pilot valve, pulp level control means foroperating said inlet valve operated by Said pilot valve and pressuremeans for closing said inlet valve and for stopping said `feedmechanism.

5. In combination with a continuous pressure filter of the classdescribed7 comprising a balanced inlet valve for the ilter, a fluidpressure cylinder and piston for operating said valve, means to controlsaid piston comprising a pilot valve and a oat resting upon the liquidin said filter, said float through the rise and fall of said liquidactuating the pilot valve to cause the piston to open and close saidbalanced valve, and means actuated by the rising of said float above apredetermined level to stop the iioiv of liquid to said balanced valve.

6. In combination with a continuous rotary pressure filter of the classdescribed, 'auto matic feed control mechanism comprising a monte-jus,pressure means to operate said monte-jus, valve mechanism controllingthe pressure in said monte-jus, valve mechanism in said filter adaptedto limit the introduction of pulp in said filter, and means to stop theoperation of said iilter and monte-jus When the pulp rises above apredetermined level.

In testimony whereofl I have aiiXed my signature to this specification.

JASPER A. MCCASKELL.

